1. Field of the Invention
The invention pertains to making fibered microscale particles by growing nanoscale fibers onto microscale spheroid particles. Syntactic foams and methods for making syntactic foams incorporating fibered microscale particles are disclosed.
2. Background Information
Syntactic foams constitute a class of composite materials typically incorporating hollow particles known as microballoons in a matrix. Because of their relatively poor flexural and tensile properties, syntactic foams generally only perform well when used in simple compression. With exterior reinforcement, syntactic foams can be used in parts functioning under more complex loadings. One such application for syntactic foams is as the core material in laminate composites having fiber-reinforced skins. Such composites are used as lightweight structures in space applications.
Improving the flexural and tensile properties of syntactic foams could allow broader use of syntactic foam in applications with complex loadings. For example, a more mechanically versatile foam might be used in space structures with thinner reinforcing skins, resulting in a lower-density structure and more engineering design flexibility.
One approach to increasing flexural strength of syntactic foams has been to admix microscale fibers into the matrix. However, on the order of 20% of the microballoons in the foam are broken during the process of dispersing the fibers in the matrix. The microballoon breakage can reduce microballoon packing efficiency and significantly decrease the compressive strength of the foam.
There is, accordingly, a need to optimize the flexural properties of syntactic foams without compromising their compressive strength and/or density.